It has been previously demonstrated that patients with advanced cancer have an important energy expenditure caused by increased tumor metabolism [41] and specifically in patients with NSCLC, also by means of chronic airway limitation [42] Therefore, serum albumin levels can be modified by tumor activity via increased FCR, but also by decreasing albumin synthesis, given that the majority of the time, patients with NSCLC display decreased appetite [43] and diminish their food intake [44]. This evidence concerns the gene ALB and neoplasm.